Dental operating lamp



E. H. GREPPIN 2,280,402

DENTAL OPERATING LAMP April 21, 1942.

Filed Aug. 10, 1939 2 Sheets-Sheet 1 INVENTOR.

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%z'sATTORNEYS April 1942- E. H. GREPPIN 2,280,402

DENTAL OPERATING LAMP Filed Aug. 10, 1939 2 Sheets-Sheet .2

M N FEW P g mil M INVENTOR. flnasiflfief nh I BY 2 z 8 4 r fig ATTORNEYSPatented Apr. 21, 1942 DENTAL OPERATING LAMP Y Ernest H. Greppin,Brighton, N. Y.,

assignor to Wilmot Castle Company, Rochester, N. Y., a corporation ofNew York Application August 10, 1939, Serial No. 289,444

4 Claims.

This invention has to do with lamps and more particularly with lamps forproviding a high intensity of illumination upon limited areas, suchlamps being useful particularly for performing surgical operations,dental work, etc. An object of the invention is to provide a generallyimproved and more satisfactory and efllcient lamp of this character.

Another object is the provision of a lamp so designed and constructedthat the beam of light projected therefrom will be confined orrestricted in one direction, such as a vertical direction when the beamextends horizontally, so that the beam may be made to shine into andprovide brilliant illumination within the mouth of a patient, forexample, without falling upon the patient's eyes.

Still another object is the provision of such a lamp in which the beamoflight, in addition to being vertically confined or restricted, is alsohorizontally expanded in a lateral direction to provide a relativelywide beam which, without readjustment of the lamp, will enter the mouthof a dental patient even when the patient moves his mouth through aconsiderable sideways range, as by turning his head.

A further object is the provision of improved color correcting means,especially adapted to an operating lamp but useful also in connectionwith any other lamp where it is desired to have a color value of higherfidelity than. that heretofore readily attainable.

To these and other ends the invention resides in certain improvementsand. combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawings:

Fig. 1 is a side elevation of a lamp constructed in accordance with apreferred embodiment of the invention; a

Fig. 2 is a fragmentary plan of the same;

Fig 3 is a central cross section taken axially through the preferredlamp;

Fig. 4 is a side view of the blocking screen and heat absorbing screen,seen from one direction;

Fig. 5 is a similar view of the same, seen from a different direction;

Fig. 6 is a face view of the lens employed in the lamp; and

Fig .7 is a diagram illustrating schematically the cross sectional shapeof the beam produced by the lamp.

the lamp is shown mounted on a preferred form of support which includes,a first arm I I mounted to swing horizontally on a substantiallyvertical axis or shaft i3 which may be mounted on a wall l5 or on anysuitable standard or support. The free end of the arm I I is connectedby a substantially vertical pivot I! to a second arm l9 provided with avertical pivot 2| on which is rotatably mounted a forked bracket 23. Thearms H and I9 are preferably hollow, to accommodate electric wiringwithin them. At the ends of the two arms of the forked bracket 23,horizontal pivots 25 (Fig. 3) extend inwardly into a generallyring-shaped fixture 21 having a handle 29 by which the fixture may beconveniently ti ted. on the forked arms. The pivot pins 25 preferablyare threaded into tapped openings in the ring 2! and are held againstrotation elative to the ring by set-screws 3|, and when the ring isoscillated relatively to the forked arms 23, the movement isaccomplished by the pins 25 turning in the arms 23. Friction washers 33may be employed between the bolt heads of the pins 25 and the arms 23,to hold the parts frictionallv in any position to which they are set.

Mounted on the ring 21 is a lamp reflector of generally concave shape,indicated in general at 4!, preferably made of a single piece of metalhaving formed, integral with the concave reflecting portion thereof, acylindrical flange or wall 43 seated within the central opening of thering 2'! and held thereto by a series of screws 45.

Back of the cylindrical flange 43 lindrical flange 41 of slightlysmaller diameter, joined thereto by a shoulder 48. Around the outside.of the flange 41 fits a cylindrical flange is a second cy- 49 on thebulb holder unit, which unit includes i The same reference numeralsthroughout the several views indicate the same parts.

a small casing 5| containing a lamp socket 53 in which a suitableincandescent bulb 55 is mounted. The flange 49 of the bulb holder unitmay be removably held on the flange 41 of the reflector by any suitablemeans, such as a bayonet type joint, or by set-screws, or simply byfriction. When the bulb holder unit is removed from the lamp, it ismoved backwardly relative to the reflector unit, the bulb 55 passing outthrough a large opening in the back of the reflector unit, within theflange 41, and the parts are quickly and easily brought together againby a reverse movement.

The bulb 55 is supplied with electric current by means of a flexiblecord 6| extending from the back of the bulb holder unit 5| into anopening at the top of the pivot 2| and downwardly through the same to asnap switch controlled by a button 63 mounted on the arm l9 beneath thepivot 2 I, the cord then extending through the hollow arm is, through asuitable recess formed at the Joint l1, and through the hollow arm lluntil thecord emerges from the bottom end of the arm II, as shown at 61,and terminates in a prong plug 69 which may be thrust into any suitablesocket 'H such as a socket formed in a lateral extension 'of the lowerbracket 13 which holds ber of generally cylindrical shape surrounds thebulb 55, as indicated at 8| in Fig. 3. This cylinder may be made ofanykind of so -called heat absorbing glass which is commonly available,such, for example, as the ferrous oxylate glass called Aklo" glass. Thecylinder is preferably of such diameter that its rear end is seated onthe shoulder 48, within the flange 43, as shown in Fig. 3. An opaquemetal plate 83 extends across and closes the front end of the heatabsorbing cylinder and is held in place by a series of coiled t-ensionedsprings 85 connected at their forward end to ears 81 on the plate 83 andconnected at their rear ends to studs 89 on the reflector unit. Thesesprings 85, constantly tending to pull the heat absorbing cylinder 8|rearwardly, hold it seated firmly against the shoulder 48 of thereflector unit.

Where it is desired to use the lamp for dental work or similar purposes,the lamp is preferably provided with an opaque metal shield or blockingmember 9| surrounding the heat absorbing cylinder 8|, as shown in Figs.3, 4, and 5. This shield 9| has the shape best shown in Figs. 4 and 5,which are side views thereof taken from two different directions atright angles to each other. As seen, the shield is in general a cylinderof about the same length as the heat absorbing cylinder 8|, on twodiametrically opposite sides. On two other diametrically opposite sidesat right anglesto the long sides, the shield is cut back so as to be ofcomparatively short axial length, the edges of the cut back portionsbeing oblique or approximately helical, as indicated at 93. The shieldis so placed in the reflector that the cut-away sides of the shield liein a plane passing along the optical axis of the unit and also passingthrough the pivot pins 25, while the long or full-length sides of theshield extend along those sides'which would be out by another axialplane at right angles to the pivot pins 25; Described another way, ifthe reflector unit is turned on its pivot on the forked arms 23 untilthe optical axis of the reflector unit is horizontal, then the cut-awaysides of the blocki'ng member 9| are at the lateral sides of the heatabsorbing cylinder 8! while the long or fulllength sides of the blockingmember are at top and bottom ofthe heat absorbing cylinder, whichcylinder now extends horizontally.

With this arrangement (again assuming for convenience of descriptionthat the lamp is turned so that its optical axis extends horizontally),the light which would otherwise pass from the fllament to the upper andlower parts of the reflector 4i, and which would be projected as theupper and lower parts of the reflected beam, is

blocked oi! by the long or full-length upper andlower walls of the metalshield or blocking member II. The light which passes laterally from thefllament, however, goes through the cutaway side walls of the shield SI,and is not intercepted thereby, but falls on the lateral side portionsof the reflecting surface and is pro- Jected as a beam which, consideredin cross section, is compressed or confined in a vertical direction(that is, in height) or flattened at top and bottom, due to the blockingeffect of the member, 9|, but which is not compressed or flattened in alateral or horizontal direction.

The purpose of blocking off the beam of light at both top and bottom,instead of at the top alone, is to provide a projected beam which is ofthe desired flattened form at its top, regardless of the distance fromthe reflector to the patient.

At some distance from the reflector, the light rays cross each other,and from that point onwardly, the rays forming the top half of the beamare those reflected from the bottom half of the reflector. By blockingoff or flattening the beam both at top and bottom at the outset, itfollows that the top of the beam falling upon the patients face will beflattened, regardless of whether he is placed inthe path of the raysbefore they cross or after they cross each other.

The front of the reflector unit is closed by a lens l0! extending acrossthe front, and according to the preferred construction this lens I0! isformed with a multiplicity of difiusing ribs, approximately parallel toeach other as indicated in the face view, Fig. 6, the direction of theribs being in the direction of a plane passing longitudinally along theoptical axis of the lamp and perpendicular to the pivotal axis definedby the pivot pins 25. In other words, these difiusing ribs will bearranged vertically when the lamp is so tilted on its pivots that itsoptical axis extends horizontally. Whenever the lamp is swung on itspivots, the diffusing ribs will still remain in vertical planes passingalong or parallel to the optical axis and perpendicular to the pivotpins 25. These diffusing ribs may, within the scope of this invention,be of various sizes, although it is usually preferred to employ a greatnumber of small ribs.

These diffusing ribs cause the beam of light passing through the lensllll to be diffused or spread in a lateral direction perpendicular tothe length of the ribs; that is, in a direction horizontally lateralwith respect to the optical axis, when the lamp is placed with itsoptical axis horizontal. Thus the beam of light is widened in a lateraldirection by the use of these diffusing ribs, and as already described,it is narrowed or flattened in a vertical direction (when the opticalaxis is horizontal) by the use of the blocking member 9|. Thecombination of the diffusing ribs and the blocking member produces aresultant beam of light which is extraordinarily satisfactory for dentaluse for illuminating the oral cavity.

The characteristics of this beam of light are 11- lustratedschematically, in a general way, in the diagram constituting Fig. '7 ofthe drawings. The dotted circle Ill indicates the shape which the crosssection of the projected beam of light would have, at any giventransverse plane, if the diffusupon the face oi. a dental patient, thebeam, due to being flattened or cut 03 at the top, will not fallupon thepatients eyes, although it will fur- ,nish adequate and brilliantillumination at the area of the mouth and in the oral cavity. Due to thehorizontal expansion or widening of the cross section of the beam oflight, the beam need not be readjusted as the patient turns his headfrom side to side, and the mouth will still be within the brilliantlyilluminated area of the beam even when it moves back and forth from sideto side, through the normal extent of movement occasioned by turning thehead from one side to the other. Hence, with this improved lamp, thedentist usually flnds it unnecessary to readjust the beam of light whenthe patient is required to turn his head one way or the other.

Another feature of the invention, particularly useful in a dental lampor other operating lamp where reasonably true color values aredesirable, is the feature of using, in conjunction with the heatabsorbing screen 8|, a material which will correct some of the colordeficiency caused by this screen.

The heatabsorbing cylinder, if made of the commonly available heatabsorbing glass as mentioned above, will unavoidably absorb asubstantially greater proportion of the visible light rays from the redend of the spectrum than those at other parts of the spectrum, and willthus shift the violet end of the spectrum. According to the presentinvention, means is provided for absorbing enough of the green rays tocompensate roughly or approximatelyfor the excess absorption of the redrays by the heat absorbing cylinder, thus shifting the color value ofthe light thereon to be reflected thereby, a cylinder of lighttransmitting and heat absorbing'materiai surrounding said source oflight and interposed in the path of travel of light therefrom towardsaid reflector, a cylindrically shaped blocking member of materialopaque to light closely surrounding said heat absorbing cylinder andblocking the travel of part of the light from said source toward saidreflector approximately along two diametrically opposite directions, tocontrol the dimensions of the beam of reflected light projected fromsaid reflector, and a light transmitting element interposed in the pathof reflected rays projected from said reflector, said transmittingelement being provided with a plurality of diil'using ribs.

2. A lamp as described in claim 1, in which said heat absorbing cylinderabsorbs a greater proportion of light rays near the red part of the Bibthe color value or the transmitted light toward passed through the heatabsorbing cylinder or screen 8|. The green absorbing fllter can be madeof cylindrical shape to surround the heat absorbing cylinder 8|, or itmay be placed in any other desired or suitable location so that thelight will pass through it either before or after being reflected by thereflector. In the preferred form, the lens "II which closes the front ofthe lamp unit constitutes the green absorbing fllter, this lens beingmade of suitable glass for absorbing a substantial proportion of thegreen rays. For instance, it may be made of glass containing selenium,or 01' any known glass having green-absorbing properties. It is foundthat the light from an incandescent light, bulb passing first throughthe heat absorbing glass BI and then through the green-absorbing lens IIII will issue from the lamp in a beam having a color value greatlyimproved over that produced if the greenlxgsorbing filtering medium isomitted.

1. A lamp including a reflector, a source of a light associated withsaid reflector to cast light visible spectrum than those at other partsthereof, and in which said light transmitting element absorbs asubstantial proportion of light rays near the green part of the visiblespectrum to improve the color value of the transmitted light bycompensating partially for the excess absorption of red by the heatabsorbing cylinder.

3. A lamp including a reflector of generally concave shape with anopening near its center and a rearwardly extending annular flange surrounding said opening, a bulb holding unit including an annular flangefor detachable engagement with said flange on said reflector and meansfor holding a light bulb in position to extend into the interior spacewithin said reflector, a heat absorbing screen of generally cylindricalform surrounding said bulb and having its rear edge seated within saidflange on said reflector, and a metal shield surrounding saidcylindrical screen and likewise having its rear edge seated within saidflange on said reflector, said shield serving to block transmission oflight rays from said bulb toward said reflector in two diametricallyopposite directions and being cut away at its sides between said twodirections to permit transmission of light rays from said bulb towardsaid reflector in diametrically opposite directions substantiallyperpendicular to the blocked directions.

4. A lamp including a reflector of generally concave shape with anopening near its center and a rearwardly extending annular flangesurrounding said opening, a bulb holding unit including an annularflange for detachable engagement with said flange on said reflector andmeans for holding a light bulb in position to extend into the interiorspace within said reflector, a heat absorbing screen of generallycylindrical form surrounding said bulb and having its rear edge seatedwithin said flange on said reflector, and a metal shield surroundingsaid cylindrical screen and likewise having its rear edge seated withinsaid flange on said reflector, said shield being of approximately thefull length of said cylindrical screen along two diametrically oppositesides and being cut away to be of materially reduced length along twoother sides between said full length sides.

ERNEST H. GREPPIN.

